2010-04-25 Antonio Gomes <tonikitoo@webkit.org>

        Reviewed by Darin Adler.

        Clicking a scrollbar blurs the currently focused element
        https://bugs.webkit.org/show_bug.cgi?id=16809

        WebKit ports that do not use native (platform) widgets for rendering the scrollbars
        are currently mismatching a common behaviour of other browser vendors (including
        Firefox and Opera): clicking on a frame scrollbar *should not* steal focus from content.
        WebKit browsers based ports that do use WebCore for handling scrollbars, like QtWebKit for
        instance, can observe the opposite behaviour.

        Patch fixes this behaviour by checking if current MouseDown event targets a frame scrollbar.
        If that is the case, it bails out and do not change focus behavior at all.

        It is important to note that the given way this is implemented by this patch, non-frame
        scrollbars (e.g. a vertical scrollbar of an overflowed textareas or divs) will keep working
        in the same way as it works currently.

        Tests: scrollbars/scrollbar-click-does-not-blur-content.html
               scrollbars/scrollbar-iframe-click-does-not-blur-content.html

        * page/EventHandler.cpp:
        (WebCore::EventHandler::dispatchMouseEve

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@58476 268f45cc-cd09-0410-ab3c-d52691b4dbfc